A projector-type display apparatus such as a liquid crystal projector and a CRT (Cathode Ray Tube) projector includes a light source, optical components, and the like. It is necessary to cool down the components heated by the light source to lower the temperature thereof. Typically, a housing of a projector-type display apparatus has an air-inlet-port. Air from the air-inlet-port flows into an air-intake fan. The intake air flows into the housing, and cools down the components.
The air-inlet-port has a filter, which blocks dust from flowing into the housing. For example, Patent Literature 1 discloses a projector-type display apparatus including a filter. The filter is attached to a housing, and is covered by a cap-for-replacing-filter. The cap has an air-inlet-port. Air flows into a housing via the air-inlet-port and the filter.